Pattern formation employing self-assembled material

ABSTRACT

In one embodiment, Hexagonal tiles encompassing a large are divided into three groups, each containing ⅓ of all hexagonal tiles that are disjoined among one another. Openings for the hexagonal tiles in each group are formed in a template layer, and a set of self-assembling block copolymers is applied and patterned within each opening. This process is repeated three times to encompass all three groups, resulting in a self-aligned pattern extending over a wide area. In another embodiment, the large area is divided into rectangular tiles of two non-overlapping and complementary groups. Each rectangular area has a width less than the range of order of self-assembling block copolymers. Self-assembled self-aligned line and space structures are formed in each group in a sequential manner so that a line and space pattern is formed over a large area extending beyond the range of order.

FIELD OF THE INVENTION

The present invention relates generally to nanoscale structures, andmore particularly to self-assembled sublithographic nanoscale structuresin a regular periodic array and methods for manufacturing for the same.

BACKGROUND OF THE INVENTION

The use of bottom-up approaches to semiconductor fabrication has grownin interest within the semiconductor industry. One such approachutilizes self-assembling block copolymers for generation ofsublithographic ground rule nanometer scale patterns.

Self-assembling copolymer materials that are capable of self-organizinginto nanometer-scale patterns may be applied within a recessed region ofa template layer to form a nanoscale structure. Under suitableconditions, the two or more immiscible polymeric block componentsseparate into two or more different phases on a nanometer scale, andthereby form ordered patterns of isolated nano-sized structural units.Such ordered patterns of isolated nano-sized structural units formed bythe self-assembling block copolymers can be used for fabricatingnano-scale structural units in semiconductor, optical, and magneticdevices. Dimensions of the structural units so formed are typically inthe range of 5 to 40 nm, which are sublithographic (i.e., below theresolution of the lithographic tools).

The self-assembling block copolymers are first dissolved in a suitablesolvent system to form a block copolymer solution, which is then appliedonto the surface of an underlayer to form a block copolymer layer. Theself-assembling block copolymers are annealed at an elevated temperatureto form two sets of polymer block structures containing two differentpolymeric block components. The polymeric block structure may be linesor cylinders. One set of polymer block structures may be embedded in theother set of polymer block structures, or polymeric block structuresbelonging to different sets may alternate. The self-assembling blockcopolymers are non-photosensitive resists, of which the patterning iseffected not by photons, i.e., optical radiation, but by self-assemblyunder suitable conditions such as an anneal.

While self-assembly of the two sets of polymer block structures by ananneal is an inherent chemical property of the self-assembling blockcopolymers, self-alignment of the two sets of polymer block structuresrequires an interaction of the self-assembling block copolymers with aphysically constraining environment. In other words, the self-alignmentof the two sets of polymer block structures requires an externalstructure to register the self-aligned structures to. Such an externalstructure functions as a template for registry of the self-alignedstructure during the anneal that separates a first polymeric blockcomponent and a second polymeric block component.

The effective range of order generated by the external structuregenerates and effecting the self-alignment of the self-assembling blockcopolymers during anneal is finite. In other words, the spatial extentof the effect of the presence of the external structure as a template islimited, and does not propagate indefinitely. The coherence of the orderis lost if the distance between the self-assembling block copolymers andthe external structure exceeds the effective range. In this case, thetwo sets of polymer block structures no longer register with theexternal structure. While the size of a self-assembled self-alignednanoscale structure may vary depending on the composition of theself-assembling block copolymers, the limited range, typicallycomprising less than 100 alterations of the first polymeric blockcomponent and the second polymeric block component. Thus, it isdifficult to form a self-assembled self-aligned nanoscale structurehaving a dimension exceeding about 1 micron.

However, a large repetitive patterned structure is highly desirable foradvanced semiconductor devices and nanoscale devices. Therefore, thereis a need for a nanoscale self-assembled self-aligned structure thatextends over a large area and having a size that is not limited byinherent effective range of the self-assembling block copolymers, andmethods of forming such a nanoscale self-assembled self-alignedstructure.

SUMMARY OF THE INVENTION

The present invention addresses the needs described above by providingcontiguous nanoscale self-assembled self-aligned structures extendingover an area extending beyond a range of order of self-assembling blockcopolymers generated by external structures, and methods ofmanufacturing the same.

In one embodiment, a large area extending beyond a coherency range oforder in self-alignment is divided into hexagonal tiles havinglithographic dimensions. The hexagonal tiles are divided into threegroups, each containing ⅓ of all hexagonal tiles that are disjoinedamong one another. The hexagonal tiles in each group are in a hexagonalarray. Openings for the hexagonal tiles in each group are formed in atemplate layer, and a set of self-assembling block copolymer is appliedand patterned within each opening. This process is repeated three timesto encompass all three groups, resulting in a self-aligned patternextending over a wide area. In a second embodiment, the large area isdivided into rectangular tiles of two non-overlapping and complementarygroups. Each rectangular area has a width less than the range of orderof self-assembling block copolymers. Self-assembled self-aligned lineand space structures are formed in each group in a sequential manner sothat a line and space pattern is formed over a large area extendingbeyond the range of order. Variations of hexagonal tiles are alsocontemplated herein such as rectangular, square, and triangular tiles.

According to an aspect of the present invention, a method of forming ananoscale pattern on a substrate is provided. The method comprises:

forming a first template layer encompassing a predefined area on asubstrate;

patterning first openings, each having a shape of a regular hexagon, inthe first template layer, wherein the first openings are arranged in afirst hexagonal array;

forming first nanoscale self-assembled self-aligned structures in thefirst openings;

forming a second template layer encompassing the area on the firstnanoscale self-assembled self-aligned structures;

patterning second openings, each having a shape of the regular hexagon,in the second template layer, wherein the second openings are arrangedin a second hexagonal array;

forming second nanoscale self-assembled self-aligned structures in thesecond openings;

forming a third template layer encompassing the area on the first andsecond nanoscale self-assembled self-aligned structures;

patterning third openings, each having a shape of the regular hexagon,in the third template layer, wherein the third openings are arranged ina third hexagonal array; and

forming third nanoscale self-assembled self-aligned structures in thethird openings.

In one embodiment, each of the first openings, the second openings, andthe third openings does not overlap any other of the first openings, thesecond openings, and the third openings.

In another embodiment, the predefined area is the same as a union ofcombined areas of the first openings, combined areas of the secondopenings, and combined areas of the third openings.

In even another embodiment, the second hexagonal array is offset fromthe first hexagonal array by one instance of the regular hexagon, thethird hexagonal array is offset from the first hexagonal array byanother instance of the regular hexagon, and the third hexagonal arrayis offset from the second hexagonal array by yet another instance of theregular hexagon.

In yet another embodiment, each of the first, second, and thirdnanoscale self-assembled self-aligned structures is congruent to anotherof the first, second, and third nanoscale self-assembled self-alignedstructures.

In still another embodiment, the method further comprises:

applying a non-photosensitive polymeric resist comprising a firstpolymeric block component and a second polymeric block component withineach of the first openings prior to the forming of first nanoscaleself-assembled self-aligned structures;

applying the non-photosensitive polymeric resist within each of thesecond openings prior to the forming of second nanoscale self-assembledself-aligned structures; and

applying the non-photosensitive polymeric resist within each of thethird openings prior to the forming of third nanoscale self-assembledself-aligned structures.

In still yet another embodiment, each of the first, second, and thirdnanoscale self-assembled self-aligned structures comprises at least onecircular cylinder comprising the first polymeric block component and apolymeric matrix comprising the second polymeric block component andlaterally abutting the at least one circular cylinder.

In a further embodiment, each of the first, second, and third nanoscaleself-assembled self-aligned structures further comprises six instancesof a third of a circular cylinder, each instance having a volume of onethird of a total volume of the at least one circular cylinder and havingan angle of 120 degrees at a ridge.

In an even further embodiment, the six instances and the polymericmatrix laterally abuts a boundary of one of the first, second, and thirdopenings.

In a yet further embodiment, each of the first, second, and thirdnanoscale self-assembled self-aligned structures comprises a pluralityof circular cylinders comprising the first polymeric block component anda polymeric matrix comprising the second polymeric block component andlaterally abutting the at least one circular cylinder, and each of theplurality of circular cylinders is disjoined from boundaries of thefirst, second, and third openings.

In a still further embodiment, the method further comprises etching oneof a set of the circular cylinders and a set of the polymeric matricesselective to the other of the set of the circular cylinders and the setof the polymeric matrices.

In further another embodiment, the method further comprises forming apattern having sublithographic dimensions in the substrate employing aremaining portion of the circular cylinders and the polymeric matricesas an etch mask.

According to another aspect of the present invention, a method offorming a nanoscale pattern on a substrate is provided. The methodcomprises:

forming a first template layer encompassing a predefined area on asubstrate;

patterning first openings, each having a shape of a rectangle and alithographic width, in the first template layer;

forming first nanoscale self-assembled self-aligned structures in thefirst openings;

forming a second template layer directly on the first nanoscaleself-assembled self-aligned structures;

patterning second openings, each having a shape of a rectangle and alithographic width, in the first template layer, wherein the secondopenings are a complement of the first openings within the predefinedarea; and

forming first nanoscale self-assembled self-aligned structures in thefirst openings.

In one embodiment, the method further comprises:

applying a non-photosensitive polymeric resist comprising a firstpolymeric block component and a second polymeric block component withineach of the first openings prior to the forming of first nanoscaleself-assembled self-aligned structures; and

applying the non-photosensitive polymeric resist within each of thesecond openings prior to the forming of second nanoscale self-assembledself-aligned structures.

In another embodiment, each of the first and second nanoscaleself-assembled self-aligned structures comprises at least one nominalwidth line and two edge lines, each comprising the first polymericcomponent, wherein each of the two edge lines abut a boundary of one ofthe first openings, wherein the at least one nominal width line isdisjoined from the two edge lines, wherein the at least one nominalwidth line has a nominal line width and the two edge lines have an edgeline width, wherein the nominal line width is sublithographic andgreater than the edge line width.

In even another embodiment, each of the first and second nanoscaleself-assembled self-aligned structures further comprises complementarylines comprising the second polymeric component, wherein each of thecomplementary lines laterally abuts two of the at least one nominalwidth line and the two edge lines and has another width that issublithographic.

In yet another embodiment, the method further comprises:

etching one of the first polymeric component and the second polymericcomponent selective to the other; and

forming a pattern having sublithographic dimensions in the substrate,wherein the pattern comprises a periodic repetition of at least onefirst line with a first sublithographic dimension and a second line witha second sublithographic dimension, wherein each neighboring pair of theat least one first line and the second line is separated by a samesublithographic spacing.

In a yet another aspect of the present invention, a structure comprisinga substrate is provided, wherein the substrate has a pattern ofprotrusion or recess from a substantially planar surface, wherein thepattern comprises a hexagonal array of a unit pattern, wherein thehexagonal array has a minimum periodicity of a lithographic dimension,wherein the unit pattern has a shape of a regular hexagon and comprisescircles of a same diameter, wherein a collection of the circles from twoneighboring instances of the unit pattern does not have hexagonalperiodicity.

In one embodiment, the same diameter is sublithographic.

In another embodiment, the pattern is a pattern of protrusion, whereinthe structure further comprises a plurality of cylinders having the samediameter, comprising a polymeric component of a non-photosensitivepolymeric resist, and located directly on each of the pattern ofprotrusion, wherein edges of the circles coincide with cylindricalsurfaces of the plurality of the cylinders.

In yet another embodiment, the pattern is a pattern of recess, whereinthe structure further comprises a matrix of a polymeric component of anon-photosensitive polymeric resist, wherein the matrix containscylindrical openings, wherein edges of the circles coincide withcylindrical surfaces of the cylindrical openings.

In a still another aspect of the present invention, a structurecomprising a substrate is provided, wherein the substrate has a onedimensional periodic repetition of a unit pattern, wherein the unitpattern comprises a protrusion or recess of at least one first line anda second line on a substantially planar surface, wherein each of the atleast one first line has a first sublithographic width, wherein thesecond line has a second sublithographic width, wherein each neighboringpair of the at least one first line and the second line is separated bya same sublithographic spacing.

In one embodiment, the first sublithographic width and the secondsublithographic width are different.

In another embodiment, the pattern is a pattern of protrusion, whereinthe structure further comprises a plurality of polymeric linescomprising a polymeric component of a non-photosensitive polymericresist and located directly on each of the at least one first line and asecond line, wherein each edge of the polymeric lines verticallycoincides with an edge of the at least one first line or the secondline.

In yet another embodiment, the pattern is a pattern of recess, whereinthe structure further comprises a plurality of polymeric linescomprising a polymeric component of a non-photosensitive polymericresist and located directly on the substantially planar surface, whereineach edge of the polymeric lines vertically coincides with an edge ofthe at least one first line or the second line.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures with the same numeric label correspond to the same stage ofmanufacturing. Figures with the suffix “A” are top-down views. Figureswith the suffix “B” or “C” are vertical cross-sectional views along theplane B-B′ or C-C′, respectively, of the corresponding figure with thesame numeric label and the suffix “A.”

FIGS. 1A-16B are sequential views of a first exemplary nanoscalestructure according to a first embodiment of the present invention.

FIGS. 17A-18B are sequential view of a variation of the first exemplarynanoscale structure according to the first embodiment of the presentinvention.

FIGS. 19A-23B are sequential view of a variation of a second exemplarynanoscale structure according to a second embodiment of the presentinvention.

FIGS. 24A and 24B are sequential view of a variation of the secondexemplary nanoscale structure according to the second embodiment of thepresent invention.

FIGS. 25A-33B are sequential view of a third exemplary nanoscalestructure according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As stated above, the present invention relates to self-assembledsublithographic nanoscale structures in a regular periodic array andmethods for manufacturing for the same, which are now described indetail with accompanying figures. It is noted that like andcorresponding elements are referred to by like reference numerals.

Referring to FIG. 1, a first exemplary nanoscale structure according toa first embodiment of the present invention comprises a first templatelayer 20A formed on a substrate 10. The lateral extent of the firsttemplate layer 20A and the substrate 10 may exceed the lateral range oforder of non-photosensitive polymeric resists to be subsequentlyemployed. The substrate 10 may be a semiconductor substrate, aninsulator substrate, a metallic substrate, or a combination thereof. Thesemiconductor substrate may be a silicon substrate, other group IVelement semiconductor substrate, or a compound semiconductor substrate.Also, the semiconductor substrate may be a bulk substrate, asemiconductor-on-insulator (SOI) substrate, or a hybrid substrate havinga bulk portion and an SOI portion. The first template layer 20A maycomprise a semiconductor material or an insulator material. Exemplarysemiconductor materials include polysilicon, amorphous silicon, apolycrystalline silicon containing alloy that include germanium orcarbon, or an amorphous silicon containing alloy that includes germaniumor silicon. Exemplary insulator materials include a dielectric oxide, adielectric oxynitride, a dielectric nitride, and a porous or non-porouslow dielectric constant insulator material (having a dielectric constantless than the dielectric constant of silicon oxide, i.e., 3.9). Further,the first template layer 20 may comprise amorphous carbon ordiamond-like carbon such as hydrogen-free amorphous carbon, tetrahedralhydrogen-free amorphous carbon, metal-containing hydrogen-free amorphouscarbon, hydrogenated amorphous carbon, tetrahedral hydrogenatedamorphous carbon, metal-containing hydrogenated amorphous carbon, andmodified hydrogenated amorphous carbon.

The first template layer 20A is first formed as a blanket layer coveringthe entirety of a top surface of the substrate 10, and subsequentlypatterned by lithographic methods employing application of a photoresist(not shown), patterning of the photoresist, and an anisotropic etch thattransfers the pattern in the photoresist into the first template layer20A. The pattern contains first openings O1 in the first template layer20A beneath which the top surface of the substrate 10 is exposed. Eachof the first openings O1 has a shape of a regular hexagon of anidentical size. Since the first openings O1 are formed by lithographicmethods, characteristic dimensions, e.g., the length of a side of theregular hexagon, are lithographic dimensions.

Whether a dimension is a lithographic dimension or a sublithographicdimension depends on whether the dimension may be formed by lithographicpatterning methods. The minimum dimension that may be formed bylithographic patterning methods is herein referred to as a “lithographicminimum dimension,” or a “critical dimension.” While the lithographicminimum dimension is defined only in relation to a given lithographytool and normally changes from generation to generation of semiconductortechnology, it is understood that the lithographic minimum dimension andthe sublithographic dimension are to be defined in relation to the bestperformance of lithography tools available at the time of semiconductormanufacturing. As of 2007, the lithographic minimum dimension is about45 nm and is expected to shrink in the future. A dimension less than thelithographic minimum dimension is a sublithographic dimension, while adimension equal to or greater than the lithographic minimum dimension isa lithographic dimension.

The location of the first openings O1 is determined by filling a topsurface of the first template layer 20A, as formed by blanket depositionor blanket application of the material comprising the first templatelayer 20A and not containing any pattern, with a hypothetical hexagonalarray of regular hexagons. The regular hexagons fill the top surface ofthe first template layer 20A in the same manner as hexagonal tiles areemployed to fill a predefined area. The boundaries of the regularhexagons are represented by broken lines in FIG. 1A. A set of one thirdof the regular hexagons comprises the first openings O1 such that eachof the regular hexagons in the set is separated from other regularhexagons in the same set and form another hexagonal array, a unithexagon of which is shown by double dotted lines in FIG. 1A. Thishexagonal array is of the first openings is herein referred to as a“first hexagonal array.” Thus, the area of the first openings O1 isapproximately one third of the entire area of the top surface of thefirst template layer 20A prior to patterning.

The length of a side of the regular hexagon is a lithographic dimension,and for example, may be greater than 45 nm. Typical range of the lengthof the side of the regular hexagon that would be practicable in 2007 isfrom about 45 nm to about 1,000 nm, and more typically, from about 45 nmto about 100 nm.

Referring to FIGS. 2A and 2B, a first non-photosensitive polymericresist is applied within each of the first openings O1 by methods wellknown in the art, such as spin coating to form first non-photosensitivepolymeric resist portions 30A. Preferably, the top surface of the firstnon-photosensitive polymeric resist portions 30A is coplanar with thetop surface of the first template layer 20A or recessed below the topsurface of the first template layer 20A. The first non-photosensitivepolymeric resist comprises self-assembling block copolymers that arecapable of self-organizing into nanometer-scale patterns.

The first non-photosensitive polymeric resist comprises a firstpolymeric block component and a second polymeric block component thatare immiscible with each other. The non-photosensitive polymeric resistmay be self-planarizing. Alternatively, the non-photosensitive polymericresist may be planarized by chemical mechanical planarization, a recessetch, or a combination thereof.

Exemplary materials for the first polymeric block component and thesecond polymeric block component are described in commonly-assigned,copending U.S. patent application Ser. No. 11/424,963, filed on Jun. 19,2006, the contents of which are incorporated herein by reference.Specific examples of self-assembling block copolymers for thenon-photosensitive polymeric resist that can be used for forming thestructural units of the present invention may include, but are notlimited to: polystyrene-block-polymethylmethacrylate (PS-b-PMMA),polystyrene-block-polyisoprene (PS-b-PI),polystyrene-block-polybutadiene (PS-b-PBD),polystyrene-block-polyvinylpyridine (PS-b-PVP),polystyrene-block-polyethyleneoxide (PS-b-PEO),polystyrene-block-polyethylene (PS-b-PE),polystyrene-b-polyorganosilicate (PS-b-POS),polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS),polyethyleneoxide-block-polyisoprene (PEO-b-PI),polyethyleneoxide-block-polybutadiene (PEO-b-PBD),polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA),polyethyleneoxide-block-polyethylethylene (PEO-b-PEE),polybutadiene-block-polyvinylpyridine (PBD-b-PVP), andpolyisoprene-block-polymethylmethacrylate (PI-b-PMMA). Theself-assembling block copolymers are first dissolved in a suitablesolvent system to form a block copolymer solution, which is then appliedonto the surface of the first exemplary structure to form thenon-photosensitive polymeric resist. The solvent system used fordissolving the block copolymer and forming the block copolymer solutionmay comprise any suitable solvent, including, but not limited to:toluene, propylene glycol monomethyl ether acetate (PGMEA), propyleneglycol monomethyl ether (PGME), and acetone. The non-photosensitivepolymeric resist is not a conventional photoresist that may be developedupon exposure to ultraviolet light or optical light. Also, thenon-photosensitive polymeric resist is not a conventional low-kdielectric material.

Referring to FIGS. 3A and 3B, a first nanoscale self-assembledself-aligned structure is formed within each of the first openings O1 bycausing cross-linking of the self-assembling block copolymers throughannealing. Specifically, the first non-photosensitive polymeric resistis annealed by ultraviolet treatment or by thermal annealing at anelevated temperature to form first columnar polymeric structures 40Acomprising the first polymeric block component and a first polymericmatrix 50A comprising the second polymeric block component and laterallyabutting the sidewalls of the first columnar polymeric structures 40A.

Exemplary processes of annealing the self-assembling block copolymers inthe block copolymer layer to form two sets of polymer blocks aredescribed in Nealey et al., “Self-assembling resists fornanolithography,” IEDM Technical Digest, December, 2005, Digital ObjectIdentifier 10.1109/IEDM.2005.1609349, the contents of which areincorporated herein by reference. Methods of annealing described in the'963 Application may be employed. The anneal may be performed, forexample, at a temperature from about 200° C. to about 300° C. for aduration from less than about 1 hour to about 100 hours.

The first columnar polymeric structures 40A comprises at least onecircular cylinder and six fractional circular cylinders eachcorresponding to one third of one of the at least one circular cylinderand contains an arc spanning an angle substantially equal to 120degrees, or 2π/3. In other words, each of the six fractional circularcylinders may be obtained by subdividing one of the at least onecircular cylinders into three equal parts by three radial cuts, eachseparated by 120 degrees and originating from a center axis of the onecircular cylinder. Thus, each of the six fractional circular cylindershas two rectangular surfaces that meet at a ridge at an angle of 120degrees. The ridge of a fractional circular cylinder is located at acorner of a regular hexagon forming one of the first nanoscaleself-assembled self-aligned structures (40A, 50A). The formation of thesix fractional circular cylinders is effected by selecting the materialfor the first template layer 20A and the first and second polymericblock components such that the first polymeric block component “wets”the walls of the first template layer 20A by surface tension. Forexample, the composition and the mean molecular weight of the firstpolymeric block component may be manipulated to make the first polymericblock component more wetting or less wetting to the surface of thematerial selected for the first template layer 20A.

The first nanoscale self-assembled self-aligned structures (40A, 50A)are “self-assembled.” The chemical composition of the firstnon-photosensitive polymeric resist is such that the immiscibility ofthe first and second polymeric block components enable self assembly ofthe first polymeric block component into the first columnar polymericstructures 40A, i.e., the at least one circular cylinder and the sixfractional circular cylinders. The second polymeric block componentassembles into the first polymeric block matrix 50A.

The first nanoscale self-assembled self-aligned structures (40A, 50A)are “self-aligned” to the walls of the first template layer 20A thatdefine the first openings O1. Specifically, each of the first nanoscaleself-assembled self-aligned structures (40A, 50A) is confined within thearea of a regular hexagon that corresponds to one of the first openingsO1 (See FIG. 1A). Further, due to self-assembly and wettingcharacteristics, each of the at least one circular cylinder and the sixfractional circular cylinders is self-aligned relative to the regularhexagon. The at least one circular cylinder may comprise a singlecylinder, seven cylinders, or any plurality of cylinders compatible withformation of a hexagonal array of cylinders within each of the firstopenings O1. In case the total number of the at least one circularcylinder exceeds seven in each of the first openings O1, half cylinders(not shown), each being equivalent to half of one of the at least onecircular cylinder, comprising the first polymeric block component may beformed within the each of the first openings O1 such that an hexagonalperiodicity is satisfied by the at least one circular cylinder, the sixfractional circular cylinders, and the half cylinders.

In one illustrative case, a “honeycomb” structure is formed with in apoly (methyl methacrylate b-styrene) (PMMA-b-S) block copolymer. In thecase of cylindrical phase diblock, the PMMA-b-S block can separate toform vertically oriented cylinders within the matrix of the polystyreneblock upon thermal annealing.

Referring to FIGS. 4A and 4B, the first template layer 20A is removedselective to the first nanoscale self-assembled self-aligned structures(40A, 50A) and the substrate 10. A wet etch or a dry etch may beemployed. The collection of the first nanoscale self-assembledself-aligned structures (40A, 50A) constitutes a hexagonal array, inwhich a unit cell comprises one instance of the first nanoscaleself-assembled self-aligned structures (40A, 50A) and a space notcontaining any of the first nanoscale self-assembled self-alignedstructures (40A, 50A) and having a volume equal to two instances of thefirst nanoscale self-assembled self-aligned structures (40A, 50A).

Referring to FIGS. 5A and 5B, a second template layer 20B is formed overthe first nanoscale self-assembled self-aligned structures (40A, 50A)and the substrate 10. The second template layer 20B may be selected fromthe materials that may be employed as the first template layer 20A. Thesecond template layer 20B may comprise the same material as, or adifferent material from, the first template layer 20A. The secondtemplate layer 20B is formed as a blanket layer and covers top surfacesof the first nanoscale self-assembled self-aligned structures (40A,50A).

Referring to FIGS. 6A and 6B, the second template layer 20B issubsequently patterned by lithographic methods employing application ofa photoresist (not shown), patterning of the photoresist, and ananisotropic etch that transfers the pattern in the photoresist into thesecond template layer 20B. The pattern contains second openings O2 inthe second template layer 20B beneath which the top surface of thesubstrate 10 is exposed. Each of the second openings O2 has a shape ofthe regular hexagon, which is the shape of the first openings O1 (SeeFIG. 1A). Since the second openings O2 are formed by lithographicmethods, characteristic dimensions, e.g., the length of a side of theregular hexagon, are lithographic dimensions.

The size and orientation of each of the second openings O2 is identicalto the size of each of the first openings O1. The location of the secondopenings O2 is obtained by shifting the pattern of the first openings O1by one regular hexagon of the size of one of the first openings O1 in adirection perpendicular to one of the sides of the regular hexagon.Thus, each instance of the second openings O2 does not overlap any ofthe first openings O1 or any other instance of the second openings O2. Aset of one third of the regular hexagons in FIG. 1A comprises the secondopenings O2 such that each of the regular hexagons in this set isseparated from other regular hexagons in the same set. The secondopenings O2 forms another hexagonal array, a unit hexagon of which isshown by double dotted lines in FIG. 6A. This hexagonal array is hereinreferred to as a “second hexagonal array.” The second hexagonal array isoffset from the first hexagonal array by an instance of the regularhexagon. The area of the second openings O2 is approximately one thirdof the entire area of the top surface of the second template layer 20Bprior to patterning.

Referring to FIGS. 7A and 7B, a second non-photosensitive polymericresist is applied within each of the second openings O2 by methods wellknown in the art, such as spin coating to form second non-photosensitivepolymeric resist portions 30B. Preferably, the top surface of the secondnon-photosensitive polymeric resist portions 30B is recessed below thetop surface of the second template layer 20B. Also preferably, the topsurface of the second non-photosensitive polymeric resist portions 30Bis coplanar with top surfaces of the first nanoscale self-assembledself-aligned structures (40A, 50A). The second non-photosensitivepolymeric resist may be applied to be coplanar with, or above, the topsurfaces of the second template layer 20B, and then recessed to theheight of the top surfaces of the first nanoscale self-assembledself-aligned structures (40A, 50A) by a recess etch or by employing adilute solution from which subsequent evaporation of a solvent causesvolume contraction within each of the second openings O2.

The second non-photosensitive polymeric resist comprises self-assemblingblock copolymers that are capable of self-organizing intonanometer-scale patterns. Thus, any of the material listed above for thefirst non-photosensitive polymeric resist may be employed for the secondnon-photosensitive polymeric resist. The second non-photosensitivepolymeric resist may comprise the same material as, or a differentmaterial from the first photosensitive polymeric resist. For thepurposes of illustrating the present invention, it is assumed that thesame material is employed for the first non-photosensitive polymericresist and the second non-photosensitive polymeric resist.

Referring to FIGS. 8A and 8B, a second nanoscale self-assembledself-aligned structure is formed within each of the second openings O2by causing cross-linking of the self-assembling block copolymers throughannealing. The same method employed for the formation of the firstnanoscale self-assembled self-aligned structures (40A, 50A) may beemployed to form the second nanoscale self-assembled self-alignedstructures.

Each of the second nanoscale self-assembled self-aligned structurescomprises second columnar polymeric structures 40B and a secondpolymeric block matrix 50B. The second columnar polymeric structures 40Bcomprises at least one circular cylinder and six fractional circularcylinders each corresponding to one third of one of the at least onecircular cylinder and contains an arc spanning an angle substantiallyequal to 120 degrees, or 2π/3. Thus, each of the second columnarpolymeric structures 40B has the same structure as one of the firstcolumnar polymeric structures 40A described above, and formed by thesame methods. The second polymeric matrix 50B comprises the secondpolymeric block component and laterally abuts each of the secondcolumnar polymeric structures 40B.

The second nanoscale self-assembled self-aligned structures (40B, 50B)are self-assembled and self-aligned in the same sense that the firstnanoscale self-assembled self-aligned structures (40A, 50A) areself-assembled and self-aligned, since the same mechanism is employedfor the self-assembly and self-alignment of the various components ofthe second nanoscale self-assembled self-aligned structures (40B, 50B).Thus, each instance of the second columnar polymeric structures 40Bcomprises the same components and is congruent to an instance of thefirst columnar polymeric structures 40A, and each instance of the secondpolymeric matrices 50B comprises the same material and is congruent toan instance of second columnar polymeric matrices 50A.

Referring to FIGS. 9A and 9B, the second template layer 20B is removedselective to the first nanoscale self-assembled self-aligned structures(40A, 50A), the second nanoscale self-assembled self-aligned structures(40B, 50B), and the substrate 10. A wet etch or a dry etch may beemployed.

Referring to FIGS. 10A-10C, a third template layer 20C is formed overthe first nanoscale self-assembled self-aligned structures (40A, 50A),the second nanoscale self-assembled self-aligned structures (40B, 50B),and the substrate 10. The third template layer 20C may be selected fromthe materials that may be employed as the first template layer 20A. Thethird template layer 20C may comprise the same material as, or adifferent material from, the first template layer 20A. The thirdtemplate layer 20C covers top surfaces of the first nanoscaleself-assembled self-aligned structures (40A, 50A) and the secondnanoscale self-assembled self-aligned structures (40B, 50B).

Referring to FIGS. 11A-11C, the third template layer 20C is subsequentlypatterned by lithographic methods employing application of a photoresist(not shown), patterning of the photoresist, and an anisotropic etch thattransfers the pattern in the photoresist into the third template layer20C. The pattern contains third openings O3 in the third template layer20C beneath which the top surface of the substrate 10 is exposed. Eachof the third openings O3 has a shape of the regular hexagon, which isthe shape of the first openings O1 (See FIG. 1A). Since the thirdopenings O3 are formed by lithographic methods, characteristicdimensions, e.g., the length of a side of the regular hexagon, arelithographic dimensions.

The size and orientation of each of the third openings O3 is identicalto the size of each of the first openings O1. The location of the thirdopenings O3 is obtained by shifting the pattern of the first openings O1by one regular hexagon of the size of one of the first openings O1 in adirection perpendicular to one of the sides of the regular hexagon suchthat the direction of shift is 60 degrees apart from the direction ofshift employed to generate the second openings O2 from the firstopenings O1. Thus, each instance of the third openings O3 does notoverlap any of the first openings O1, the second openings O2, or anyother instance of the third openings O3. A set of one third of theregular hexagons in FIG. 1A comprises the third openings O3 such thateach of the regular hexagons in this set is separated from other regularhexagons in the same set. The third openings O3 forms another hexagonalarray, a unit hexagon of which is shown by double dotted lines in FIG.11A. This hexagonal array is herein referred to as a “third hexagonalarray.” The third hexagonal array is offset from the first hexagonalarray by an instance of the regular hexagon. The third hexagonal arrayis also offset from the second hexagonal array by another instance ofthe regular hexagon. The area of the third openings O3 is approximatelyone third of the entire area of the top surface of the third templatelayer 20C prior to patterning.

Referring to FIGS. 12A and 12B, a third non-photosensitive polymericresist is applied within each of the third openings O3 by methods wellknown in the art, such as spin coating to form third non-photosensitivepolymeric resist portions 30C. Preferably, the top surface of the thirdnon-photosensitive polymeric resist portions 30C is recessed below thetop surface of the third template layer 20C. Also preferably, the topsurface of the third non-photosensitive polymeric resist portions 30C iscoplanar with top surfaces of the first nanoscale self-assembledself-aligned structures (40A, 50A) and the second nanoscaleself-assembled self-aligned structures (40B, 50B). The thirdnon-photosensitive polymeric resist may be applied to be coplanar with,or above, the top surfaces of the third template layer 30C, and thenrecessed to the height of the top surfaces of the first nanoscaleself-assembled self-aligned structures (40A, 50A) by a recess etch, orby employing a dilute solution from which subsequent evaporation of asolvent causes volume contraction within each of the third openings O3.

The third non-photosensitive polymeric resist comprises self-assemblingblock copolymers that are capable of self-organizing intonanometer-scale patterns. Thus, any of the material listed above for thefirst non-photosensitive polymeric resist may be employed for the thirdnon-photosensitive polymeric resist. The third non-photosensitivepolymeric resist may comprise the same material as, or a differentmaterial from the first photosensitive polymeric resist. For thepurposes of illustrating the present invention, it is assumed that thesame material is employed for the first non-photosensitive polymericresist and the third non-photosensitive polymeric resist.

Referring to FIGS. 13A and 13B, a third nanoscale self-assembledself-aligned structure is formed within each of the third openings O3 bycausing cross-linking of the self-assembling block copolymers throughannealing. The same method employed for the formation of the first thirdnanoscale self-assembled self-aligned structures (40A, 50A) may beemployed to form the third nanoscale self-assembled self-alignedstructures.

Each of the third nanoscale self-assembled self-aligned structurescomprises third columnar polymeric structures 40C and a second polymericblock matrix 50C. The third columnar polymeric structures 40C comprisesat least one circular cylinder and six fractional circular cylinderseach corresponding to one third of one of the at least one circularcylinder and contains an arc spanning an angle substantially equal to120 degrees, or 2π/3. Thus, each of the third columnar polymericstructures 40C has the same structure as one of the first columnarpolymeric structures 40A described above, and formed by the samemethods. The third polymeric matrix 50C comprises the second polymericblock component and laterally abuts each of the third columnar polymericstructures 40C.

The third nanoscale self-assembled self-aligned structures (40C, 50C)are self-assembled and self-aligned in the same sense that the firstnanoscale self-assembled self-aligned structures (40A, 50A) areself-assembled and self-aligned, since the same mechanism is employedfor the self-assembly and self-alignment of the various components ofthe third nanoscale self-assembled self-aligned structures (40C, 50C).Thus, each instance of the third columnar polymeric structures 40Ccomprises the same components and is congruent to an instance of thefirst columnar polymeric structures 40A, and each instance of the thirdpolymeric matrices 50C comprises the same material and is congruent toan instance of third columnar polymeric matrices 50A.

Referring to FIGS. 14A-14C, the third template layer 20C is removedselective to the first nanoscale self-assembled self-aligned structures(40A, 50A), the second nanoscale self-assembled self-aligned structures(40B, 50B), and the third nanoscale self-assembled self-alignedstructures (40C, 50C). A wet etch or a dry etch may be employed.

The various fractional circular cylinders and half cylinders, ifpresent, combine to form a full cylinder having a circular horizontalcross-sectional area having the same diameter as cross-sectional areasof the various circular cylinders. Irrespective of whether any cylindercomprising the first polymeric block component is formed from only oneof the first, second, and third non-photosensitive polymeric resists orfrom at least two of the first, second, and third non-photosensitivepolymeric resists, all such circular cylinders are herein collectivelytermed circular polymeric cylinders. In other words, the first, second,and third columnar polymeric structures (40A, 40B, 40C) collectivelyconstitute the circular polymeric cylinders.

Referring to FIGS. 15A and 15B, the first, second, and third polymericblock matrices (50A, 50B, 50C) are removed selective to the first,second, and third columnar polymeric structures (40A, 40B, 40C) by anetch that removes the second polymeric block component selective to thefirst polymeric block component. This etch may be isotropic oranisotropic. After removal of the first, second, and third polymericblock matrices (50A, 50B, 50C), an hexagonal array of circular polymericcylinders 40 is formed on the substrate 10, i.e., the circular polymericcylinders 40 are arranged to form the hexagonal array in which theperiodicity of hexagonal array is the same as the distance between anadjacent pair of axes of the circular polymeric cylinders 40.

Referring to FIGS. 16A and 16B, the pattern of the hexagonal array ofthe circular polymeric cylinders 40 is transferred into the substrate 10by an anisotropic etch that removes exposed portions of the substrate 10selective to the circular polymeric cylinders 40. A recessed surface 11of the substrate 10 is exposed underneath the interface between thesubstrate 10 and the hexagonal array of the circular polymeric cylinders40. The recessed surface 11 contains a plurality of holes that coincidewith the location of the hexagonal array of the circular polymericcylinders 40. Since the diameter of the circular polymeric cylinders 40may be sublithographic, the pattern of the recessed surface 11 maycontain a sublithographic unit pattern.

Upon removal of the hexagonal array of the circular polymeric cylinders40 selective to the substrate 10, a structure comprising the substrate10 is provided, in which the substrate 10 has a pattern of protrusionfrom a substantially planar surface, which is the recessed surface 11.The pattern comprises a hexagonal array of a unit pattern, which is acircular cylinder having a substantially the same diameter as one of thecircular polymeric cylinders 40. The hexagonal array may have a minimumperiodicity of a sublithographic dimension.

Referring to FIGS. 17A and 17B, a variation of the first exemplarynanoscale structure is formed from the first exemplary nanoscalestructure of FIGS. 14A-14C by removing the first, second, and thirdcolumnar polymeric structures (40A, 40B, 40C) selective to thecombination of the first, second, and third polymeric block matrices(50A, 50B, 50C), which is herein referred to as a combined polymericblock matrices 50. An etch that removes the first polymeric blockcomponent selective to the second polymeric block component is employed.This etch may be isotropic or anisotropic.

After removal of the first, second, and third columnar polymericstructures (40A, 40B, 40C), a hexagonal array of cylindrical cavities isformed in the combined polymeric block matrices 50. In other words, thecylindrical cavities in the combined polymeric block matrices 50 arearranged to form the hexagonal array in which the periodicity ofhexagonal array is the same as the distance between an adjacent pair ofaxes of the cylindrical cavities.

Referring to FIGS. 18A and 18B, the pattern of the hexagonal array ofthe cylindrical cavities is transferred into the substrate 10 by ananisotropic etch that removes exposed portions of the substrate 10selective to the combined polymeric block matrices 50. Recessed trenchbottom surfaces 12 of the substrate 10 are formed by removal of thematerial of the substrate from the cylindrical cavities within thecombined polymeric block matrices 50. The cylindrical trenches withinthe substrate 10 are arranged in a hexagonal array. Since the diameterof the cylindrical trenches may be sublithographic, the pattern of thecylindrical trenches may contain a sublithographic unit pattern.

Upon removal of the hexagonal array of the combined polymeric blockmatrices 50 selective to the substrate 10, a structure comprising thesubstrate 10 is provided, in which the substrate 10 has a pattern ofrecess from a substantially planar surface, which is the recessed trenchbottom surfaces 12. The pattern comprises a hexagonal array of a unitpattern, which is a circular trench having a substantially the samediameter as one of the circular polymeric cylinders 40. The hexagonalarray may have a minimum periodicity of a sublithographic dimension.

According to a second embodiment of the present invention, a secondexemplary nanoscale structure is derived from the first exemplarynanoscale structure of FIGS. 1A-2B. To form the second exemplarynanoscale structure, however, the wetting characteristics of the firstand second polymeric block components are modified such that the firstpolymeric block component does not wet the surface of the first templatelayer 20A, while the second polymeric block component wets the surfaceof the first template layer 20A.

Referring to FIGS. 19A and 19B, a first nanoscale self-assembledself-aligned structure is formed within each of the first openings O1(See FIGS. 1A and 1B) by causing cross-linking of the self-assemblingblock copolymers through annealing. The same annealing process may beemployed as in the first embodiment. The first nanoscale self-assembledself-aligned structure is formed within each of the first openings O1 bycausing cross-linking of the self-assembling block copolymers throughannealing. Specifically, the first non-photosensitive polymeric resistis annealed by ultraviolet treatment or by thermal annealing at anelevated temperature to form first columnar polymeric structures 40Acomprising the first polymeric block component and a first polymericmatrix 50A comprising the second polymeric block component and laterallyabutting the sidewalls of the first columnar polymeric structures 40A.The first columnar polymeric structures 40A do not contact the sidewallsof the first openings O1, while the first polymeric matrix 50A abutssidewalls of the first template layer 20A in each of the first openingsO1. The first nanoscale self-assembled self-aligned structures (40A,50A) are “self-assembled” and “self-aligned” due to the same mechanismas in the first embodiment.

Referring to FIGS. 20A and 20B, the first template layer 20A is removedselective to the first nanoscale self-assembled self-aligned structures(40A, 50A) and the substrate 10. A wet etch or a dry etch may beemployed. The collection of the first nanoscale self-assembledself-aligned structures (40A, 50A) constitutes a hexagonal array, inwhich a unit cell comprises one instance of the first nanoscaleself-assembled self-aligned structures (40A, 50A) and a space notcontaining any of the first nanoscale self-assembled self-alignedstructures (40A, 50A) and having a volume equal to two instances of thefirst nanoscale self-assembled self-aligned structures (40A, 50A).

Referring to FIGS. 21A and 21B, a second template layer 20B is formedover the first nanoscale self-assembled self-aligned structures (40A,50A) and the substrate 10. The second template layer 20B may be selectedfrom the materials that may be employed as the first template layer 20A.The second template layer 20B may comprise the same material as, or adifferent material from, the first template layer 20A. The secondtemplate layer 20B is formed as a blanket layer and covers top surfacesof the first nanoscale self-assembled self-aligned structures (40A,50A).

Processing steps corresponding to FIGS. 6A-13B of the first embodimentare performed to form second nanoscale self-assembled self-alignedstructures (40B, 50B) and third nanoscale self-assembled self-alignedstructures (40C, 50C). By modulating the wetting characteristics of thefirst and second polymeric block components, the second columnarpolymeric structures 40B do not contact the sidewalls of the secondopenings O2, while each of the second polymeric matrices 50B abutssidewalls of the second template layer 20B in each of the secondopenings O2. Likewise, the third columnar polymeric structures 40B donot contact the sidewalls of the third openings O3, while each of thethird polymeric matrices 50B abuts sidewalls of the third template layer20C in each of the third openings O3.

Referring to FIGS. 22A and 22B, the third template layer 20C is removedselective to the first nanoscale self-assembled self-aligned structures(40A, 50A), the second nanoscale self-assembled self-aligned structures(40B, 50B), and the third nanoscale self-assembled self-alignedstructures (40C, 50C). A wet etch or a dry etch may be employed.

Referring to FIGS. 23A and 23B, the first, second, and third polymericblock matrices (50A, 50B, 50C) are removed selective to the first,second, and third columnar polymeric structures (40A, 40B, 40C) by anetch that removes the second polymeric block component selective to thefirst polymeric block component. This etch may be isotropic oranisotropic. The first, second, and third columnar polymeric structures(40A, 40B, 40C) collectively constitute circular polymeric cylinders 40.The circular polymeric cylinders 40 are arranged to form a hexagonalarray. However, the periodicity of the hexagonal array is not the sameas the distance between an adjacent pair of axes of the circularpolymeric cylinders 40. Instead, the hexagonal array has a unit cellhaving the same size as each of the first openings O1, second openingsO2, third openings O3 (See FIGS. 1A, 6A, and 11A, respectively) andcontains a plurality of circular polymeric cylinders 40. Two exemplaryunit cells of the hexagonal array are labeled “G1” and “G2”.

The pattern of the hexagonal array of the circular polymeric cylinders40 is transferred into the substrate 10 by an anisotropic etch thatremoves exposed portions of the substrate 10 selective to the circularpolymeric cylinders 40. A recessed surface 11 of the substrate 10 isexposed underneath the interface between the substrate 10 and thehexagonal array of the circular polymeric cylinders 40. The recessedsurface 11 contains a plurality of holes that coincide with the locationof the hexagonal array of the circular polymeric cylinders 40. Since thediameter of the circular polymeric cylinders 40 may be sublithographic,the pattern of the recessed surface 11 may contain a sublithographicunit pattern.

Upon removal of the hexagonal array of the circular polymeric cylinders40 selective to the substrate 10, a structure comprising the substrate10 is provided, in which the substrate 10 has a pattern of protrusionfrom a substantially planar surface, which is the recessed surface 11.The pattern comprises a hexagonal array of a unit pattern, e.g., G1 orG2, which comprises a plurality of circular cylinders of integralconstruction with the substrate 10, i.e., being a part of the substrate10, and having a substantially the same diameter as one of the circularpolymeric cylinders 40. The hexagonal array has a minimum periodicity ofa lithographic dimension. The unit pattern, e.g., G1 or G2, has a shapeof a regular hexagon and comprises circles of a same diameter, which isthe diameter of each of the circular polymeric cylinders 40. However, acollection of the circles from two neighboring instances of the unitpattern does not have hexagonal periodicity. For example, the collectionof circles in the union set of G1 and G2 does not have hexagonalperiodicity since the coherency of any hexagonal periodicity of thecircular polymeric cylinders 40 does not extend beyond an area of one ofthe first, second, and third openings (O1, O2, O3).

Referring to FIGS. 24A and 24B, a variation of the second exemplarynanoscale structure is formed from the second exemplary nanoscalestructure of FIGS. 22A-22B by removing the first, second, and thirdcolumnar polymeric structures (40A, 40B, 40C) selective to thecombination of the first, second, and third polymeric block matrices(50A, 50B, 50C), which is herein referred to as a combined polymericblock matrices 50. An etch that removes the first polymeric blockcomponent selective to the second polymeric block component is employed.This etch may be isotropic or anisotropic.

After removal of the first, second, and third columnar polymericstructures (40A, 40B, 40C), an array of cylindrical cavities is formedin the combined polymeric block matrices 50. The pattern of the array ofthe cylindrical cavities is transferred into the substrate 10 by ananisotropic etch that removes exposed portions of the substrate 10selective to the combined polymeric block matrices 50. Recessed trenchbottom surfaces 12 of the substrate 10 are formed by removal of thematerial of the substrate from the cylindrical cavities within thecombined polymeric block matrices 50. The cylindrical trenches withinthe substrate 10 are arranged to form a hexagonal array. However, theperiodicity of the hexagonal array is not the same as the distancebetween an adjacent pair of axes of the cylindrical trenches. Instead,the hexagonal array has a unit cell having the same size as each of thefirst openings O1, second openings O2, third openings O3 (See FIGS. 1A,6A, and 11A, respectively) and contains a plurality of cylindricaltrenches. Two exemplary unit cells of the hexagonal array are labeled“G3” and “G4”.

Upon removal of the combined polymeric block matrices 50 selective tothe substrate 10, a structure comprising the substrate 10 is provided,in which the substrate 10 has a pattern of recess from a substantiallyplanar surface, which is the top surface of the substrate 10, i.e., theformer interface between the substrate 10 and the combined polymericblock matrices 50. The pattern comprises a hexagonal array of a unitpattern, e.g., G3 or G4, which comprises a plurality of the cylindricaltrenches with the substrate 10, i.e., and having a substantially thesame diameter as one of the circular polymeric cylinders 40. Thehexagonal array has a minimum periodicity of a lithographic dimension.The unit pattern, e.g., G3 or G4, has a shape of a regular hexagon andcomprises circles of a same diameter, which is the diameter of each ofthe circular cylindrical trenches. However, a collection of the circlesfrom two neighboring instances of the unit pattern does not havehexagonal periodicity. For example, the collection of circles in theunion set of G3 and G4 does not have hexagonal periodicity since thecoherency of any hexagonal periodicity of the cylindrical trenches doesnot extend beyond an area of one of the first, second, and thirdopenings (O1, O2, O3).

Referring to FIGS. 25A and 25B, a third exemplary nanoscale structureaccording to a third embodiment of the present invention is shown, whichcomprises a substrate 10 and a first template layer 20A. The lateralextent of the first template layer 20A and the substrate 10 may exceedlateral range of order of non-photosensitive polymeric resists to besubsequently employed. The substrate 10 and the first template layer 20Amay comprise the same materials as, and may be formed by the samemethods as, in the first embodiment.

The first template layer 20A is patterned with first rectangularopenings to expose the substrate 10. The lateral width of each firstrectangular opening is lithographic. Further, the spacing betweenadjacent first rectangular openings is also lithographic. While thewidths of the first rectangular openings may vary from opening toopening, the same lateral width of the first rectangular openings areassumed to be the same for the purposes of description of the presentinvention, which is herein referred to as a first lateral width LW1.Likewise, the spacing between adjacent first rectangular openings isassumed to be the same for the purposes of description of the presentinvention, which is herein referred to as a second lateral width LW2.Embodiments in which the first rectangular openings have differentlateral widths and/or the adjacent first rectangular openings havedifferent spacings are explicitly contemplated herein.

The lengthwise direction of each first rectangular opening issufficiently greater than the first lateral width LW1 to causesubsequent formation of self-aligned patterns along the lengthwisedirection of the first rectangular openings, i.e., in the directionperpendicular to the direction of the lateral widths of the firstrectangular openings.

Referring to FIGS. 26A and 26B, a first non-photosensitive polymericresist is applied within each of the first rectangular openings bymethods well known in the art, such as spin coating to form firstnon-photosensitive polymeric resist portions 30A. Preferably, the topsurface of the first non-photosensitive polymeric resist portions 30A iscoplanar with the top surface of the first template layer 20A orrecessed below the top surface of the first template layer 20A. Thefirst non-photosensitive polymeric resist comprises self-assemblingblock copolymers that are capable of self-organizing intonanometer-scale patterns.

The first non-photosensitive polymeric resist comprises a firstpolymeric block component and a second polymeric block component thatare immiscible with each other. The non-photosensitive polymeric resistmay be self-planarizing. Alternatively, the non-photosensitive polymericresist may be planarized by chemical mechanical planarization, a recessetch, or a combination thereof. The same material may be employed forthe first polymeric block component and the second polymeric blockcomponent as in the first embodiment. Also, the same application methodmay be employed as in the first embodiment.

Referring to FIGS. 27A and 27B, a first nanoscale self-assembledself-aligned structure NS1 is formed within each of the firstrectangular openings by causing cross-linking of the self-assemblingblock copolymers through annealing. Specifically, the firstnon-photosensitive polymeric resist is annealed by ultraviolet treatmentor by thermal annealing at an elevated temperature to form first primarylamellar structures 43A comprising the first polymeric block componentand first complementary lamellar structures 53A comprising the secondpolymeric block component. The first primary lamellar structure 43A andthe first complementary lamellar structures 53A alternate withperiodicity in the direction of the first lateral width LW1.

The composition and wetting properties of the first non-photosensitivepolymeric resist is adjusted such that some of the first primarylamellar structures 43A abut the sidewalls of the first template layer20A, while the first complementary lamellar structures 53A are disjoinedfrom the sidewalls of the first template layer 20A. The wettingcharacteristics of the first polymeric block component is tuned so thatthe width of a first primary lamellar structure 43A depends on whetherthe first primary lamellar structure 43A contacts the sidewalls of thefirst template layer 20A or not. The width of the first primary lamellarstructure 43A that does not contact the sidewalls of the first templatelayer 20A is herein referred to as a first width W1. The width of thefirst primary lamellar structure 43A that contacts the sidewalls of thefirst template layer 20A is herein referred to as a second width W2. Thefirst width W1 and the second width W2 may be both sublithographic, forexample, in the range from about 1 nm to about 40 nm, and typically fromabout 5 nm to about 30 nm. The first width W1 is greater than the secondwidth W2. The first width W1 may be greater than, equal to, or lessthan, twice the second width W2. The width of the first complementarylamellar structures 53A is the same, and is herein referred to as alamellar spacing S, which may be sublithographic. The sum of the firstwidth W1 and the lamellar spacing S may also be sublithographic.

The first nanoscale self-assembled self-aligned structures NS1 are“self-assembled.” The chemical composition of the firstnon-photosensitive polymeric resist is such that the immiscibility ofthe first and second polymeric block components enable self assembly ofthe first polymeric block component into the first primary lamellarstructures 43A and the second polymeric block component assembles intothe first complementary lamellar structures 53A.

The first nanoscale self-assembled self-aligned structures NS1 are“self-aligned” to the walls of the first template layer 20A that definethe rectangular openings. The first primary lamellar structures 43A andfirst complementary lamellar structures 53A run along the lengthwisedirection of the rectangular openings in the first template layer 20A.

The first template layer 20A is subsequently removed selective to thefirst nanoscale self-assembled self-aligned structures NS1 and thesubstrate 10. A wet etch or a dry etch may be employed.

Referring to FIGS. 28A and 28B, a second template layer 20B is formedover the first nanoscale self-assembled self-aligned structures NS1 andthe substrate 10. The second template layer 20B may be selected from thematerials that may be employed as the first template layer 20A. Thesecond template layer 20B may comprise the same material as, or adifferent material from, the first template layer 20A. The secondtemplate layer 20B is formed as a blanket layer and covers top surfacesof the first nanoscale self-assembled self-aligned structures NS1.

The second template layer 20B is lithographically patterned by applyinga photoresist (not shown), lithographic patterning of the photoresist,and transfer of the pattern in the photoresist into the second templatelayer by an anisotropic etch. A set of second rectangular openings,which covers a complementary area of the first rectangular openings, isformed in the second template layer 20B. Thus, the second rectangularopenings are formed between the first nanoscale self-assembledself-aligned structures NS1, and the boundaries of the secondrectangular openings substantially coincide with the boundaries of thefirst nanoscale self-assembled self-aligned structures NS1. The width ofeach of the second rectangular openings is the second lateral width LW2,which is a lithographic dimension, and may be the same as, or differentfrom, the first lateral width LW1.

Referring to FIGS. 29A and 29B, a second non-photosensitive polymericresist is applied within each of the second rectangular openings bymethods well known in the art, such as spin coating to form secondnon-photosensitive polymeric resist portions 30B. Preferably, the topsurface of the second non-photosensitive polymeric resist portions 30Bis recessed below the top surface of the second template layer 20B. Alsopreferably, the top surface of the second non-photosensitive polymericresist portions 30B is coplanar with top surfaces of the first nanoscaleself-assembled self-aligned structures NS1. The secondnon-photosensitive polymeric resist may be applied to be coplanar with,or above, the top surfaces of the second template layer 20B, and thenrecessed to the height of the top surfaces of the first nanoscaleself-assembled self-aligned structures NS1 by a recess etch or byemploying a dilute solution from which subsequent evaporation of asolvent causes volume contraction within each of the second rectangularopenings.

The second non-photosensitive polymeric resist comprises self-assemblingblock copolymers that are capable of self-organizing intonanometer-scale patterns. Thus, any of the material listed above for thefirst non-photosensitive polymeric resist may be employed for the secondnon-photosensitive polymeric resist. The second non-photosensitivepolymeric resist may comprise the same material as, or a differentmaterial from the first photosensitive polymeric resist. For thepurposes of illustrating the present invention, it is assumed that thesame material is employed for the first non-photosensitive polymericresist and the second non-photosensitive polymeric resist.

Referring to FIGS. 30A and 30B, a second nanoscale self-assembledself-aligned structure NS2 is formed within each of the secondrectangular openings by causing cross-linking of the self-assemblingblock copolymers through annealing. The same method employed for theformation of the first nanoscale self-assembled self-aligned structureNS1 may be employed to form the second nanoscale self-assembledself-aligned structures NS2.

Specifically, the second non-photosensitive polymeric resist is annealedby ultraviolet treatment or by thermal annealing at an elevatedtemperature to form second primary lamellar structures 43B comprisingthe first polymeric block component and second complementary lamellarstructures 53B comprising the second polymeric block component. Thesecond primary lamellar structure 43B and the second complementarylamellar structures 53B alternate with periodicity in the direction ofthe second lateral width LW2.

The composition and wetting properties of the second non-photosensitivepolymeric resist is adjusted such that some of the second primarylamellar structures 43B abut the exposed sidewalls of the first primarylamellar structures 43A, while the second complementary lamellarstructures 53B are disjoined from the sidewalls of the first primarylamellar structures 53B. The wetting characteristics of the firstpolymeric block component is tuned so that the width of a second primarylamellar structure 43B depends on whether the second primary lamellarstructure 43B contacts the sidewalls of the first primary lamellarstructures 43A or not. Preferably, the width of the second primarylamellar structure 43B that does not contact the sidewalls of a firstprimary lamellar structure 43A is the same as the first width W1. Thewidth of the second primary lamellar structure 43B that contacts thesidewalls of a first primary lamellar structure 43A may, or may not, bethe same as the second width W2. The width of the second complementarylamellar structures 53B is the same among themselves, and may be thesame as, or different from, the lamellar spacing S, which is the widthof a first complementary lamellar structure 53A.

The second nanoscale self-assembled self-aligned structures NS2 areself-assembled and self-aligned in the same sense that the firstnanoscale self-assembled self-aligned structures NS1 are self-assembledand self-aligned, since the same mechanism is employed for theself-assembly and self-alignment of the various components of the secondnanoscale self-assembled self-aligned structures NS2.

Referring to FIGS. 31A and 31B, the second template layer 20B is removedselective to the first nanoscale self-assembled self-aligned structuresNS1, the second nanoscale self-assembled self-aligned structures NS2,and the substrate 10. A wet etch or a dry etch may be employed.

Referring to FIGS. 32A and 32B, the first and second complementarylamellar structures (53A, 53B) are removed selective to the first andsecond primary lamellar structures (43A, 43B) by an anisotropic etchthat removes the second polymeric block component selective to the firstpolymeric block component. The set of first primary lamellar structures43A from the same first rectangular opening constitutes a first onedimensional arrays A1 having a spacing of the lamellar spacing S.Likewise, the set of second primary lamellar structures 43B from thesame second rectangular opening constitutes a second one dimensionalarrays A2 having a spacing of the lamellar spacing S. However, anadjacent pair of a first one dimensional array A1 and a second onedimensional array A2 may, or may not, be coherent, i.e., constituteanother one dimensional array with periodicity. If the second width W2is one half of the first width, the collection of the first onedimensional arrays A1 and the second one dimensional arrays A2constitute an extended one dimensional array having a periodicity of thesum of the first width W1 and the lamellar spacing S. However, if thesecond width W2 is not equal to one half of the first width W1, theextended one dimensional array comprising a plurality of the first onedimensional arrays A1 and the second one dimensional arrays A2 has aperiodicity of the sum of the first lateral width LW1 and the secondlateral width LW2. Thus, the minimum periodicity is a lithographicdimension.

Referring to FIGS. 33A and 33B, the pattern of the extended arraycomprising the first one dimensional arrays A1 and the second onedimensional arrays A2 is transferred into the substrate 10 by ananisotropic etch that removed exposed portions of the substrate 10selective to the first and second primary lamellar structures (43A,43B). Linear trenches are formed within the substrate to expose trenchbottom surfaces 13 at the bottom of the linear trenches. The first andsecond primary lamellar structures (43A, 43B) may be subsequentlyremoved.

The third exemplary nanoscale structure comprises a substrate 10 havinga one dimensional periodic repetition of a unit pattern. The unitpattern comprises protrusion of at least one first line and a secondline on a substantially planar surface, which is the collection of thetrench bottom surfaces 13. Each of the at least one first line is formeddirectly underneath a first primary lamellar structure 43A not abuttinga second lamellar structure 43B or directly underneath a second primarylamellar structures 43B not abutting a first lamellar structure 43A. Thesecond line is formed directly underneath a first primary lamellarstructure 43A abutting a second primary lamellar structure 43B. Each ofthe at least one first line may have a first sublithographic width,which is the first width W1, and second line has a secondsublithographic width, which is twice the second width W2. Eachneighboring pair of the at least one first line and the second line maybe separated by a same sublithographic spacing, which is the lamellarspacing S.

The first sublithographic width and the second sublithographic width arethe same if the first width W1 is twice the second width W2. The onedimensional unit pattern has a minimum periodicity that is equal to thesum of the first width W1 and the lamellar spacing S. However, the firstsublithographic width and the second sublithographic width are differentif the first width W1 is not twice the second width W2. If the firstlateral width LW1 and the second lateral width LW2 are the same, the onedimensional unit pattern has a minimum periodicity that is equal to thefirst lateral width LW1, which is a lithographic dimension. If the firstlateral width LW1 and the second lateral width LW2 are different, theone dimensional unit pattern has a minimum periodicity that is equal tothe sum of the first lateral width LW1 and the second lateral width LW2,which is a lithographic dimension.

Prior to removal of the first and second primary lamellar structures(43A, 43B), the third exemplary nanoscale structure further comprises aplurality of polymeric lines, which are the first and second primarylamellar structures (43A, 43B) and comprises a polymeric component of anon-photosensitive polymeric resist and located directly on each of theat least one first line and a second line. Each edge of the polymericlines vertically coincides with an edge of the at least one first lineor the second line.

Instead of removing the first and second complementary lamellarstructures (53A, 53B) selective to the first and second primary lamellarstructures (43A, 43B) from the third exemplary nanoscale structure ofFIGS. 31A and 31B, the first and second primary lamellar structures(43A, 43B) may be selected relative to the first and secondcomplementary lamellar structures (53A, 53B). The pattern of the firstand second primary lamellar structures (43A, 43B) may then betransferred into the substrate 10 to form another nanoscale structurewhich has the opposite polarity as the structure of FIGS. 33A and 33B.The resulting pattern is a pattern of recess instead of protrusions, inwhich the structure further comprises a plurality of polymeric linescomprising a polymeric component of a non-photosensitive polymericresist and located directly on the substantially planar surface, andeach edge of the polymeric lines vertically coincides with an edge ofthe at least one first line or the second line.

Variation on the geometry of the tiles or openings is also contemplated.The tiles or openings may include one shape, e.g., a hexagon, arectangle, a rhombus, a parallelogram, a triangle, or a regular polygon,or may comprise a collection of at least two different shapes.

While the invention has been described in terms of specific embodiments,it is evident in view of the foregoing description that numerousalternatives, modifications and variations will be apparent to thoseskilled in the art. Accordingly, the invention is intended to encompassall such alternatives, modifications and variations which fall withinthe scope and spirit of the invention and the following claims.

1. A method of forming a nanoscale pattern on a substrate, said methodcomprising: forming a first template layer encompassing a predefinedarea on a substrate, wherein an entirety of a bottom surface of saidfirst template layer is planar; patterning first openings, each having ashape of a regular hexagon, in said first template layer, wherein saidfirst openings are arranged in a first hexagonal array; forming firstnanoscale self-assembled self-aligned structures in said first openings;forming a second template layer encompassing said area on said firstnanoscale self-assembled self-aligned structures; patterning secondopenings, each having a shape of said regular hexagon, in said secondtemplate layer, wherein said second openings are arranged in a secondhexagonal array; forming second nanoscale self-assembled self-alignedstructures in said second openings; forming a third template layerencompassing said area on said first and second nanoscale self-assembledself-aligned structures; patterning third openings, each having a shapeof said regular hexagon, in said third template layer, wherein saidthird openings are arranged in a third hexagonal array; and formingthird nanoscale self-assembled self-aligned structures in said thirdopenings.
 2. The method of claim 1, wherein each of said first openings,said second openings, and said third openings does not overlap any otherof said first openings, said second openings, and said third openings.3. The method of claim 2, wherein said predefined area is the same as aunion of combined areas of said first openings, combined areas of saidsecond openings, and combined areas of said third openings.
 4. Themethod of claim 1, wherein said second hexagonal array is offset fromsaid first hexagonal array by one instance of said regular hexagon,wherein said third hexagonal array is offset from said first hexagonalarray by another instance of said regular hexagon, and wherein saidthird hexagonal array is offset from said second hexagonal array by yetanother instance of said regular hexagon.
 5. The method of claim 1,wherein each of said first, second, and third nanoscale self-assembledself-aligned structures is congruent to another of said first, second,and third nanoscale self-assembled self-aligned structures.
 6. Themethod of claim 1, wherein each of said first openings, said secondopenings, and said third openings is patterned by application of aphotoresist, patterning of said photoresist, and an anisotropic etchthat transfers a pattern in said photoresist into one of said firsttemplate layer, said second template layer, and said third templatelayer.
 7. A method of forming a nanoscale pattern on a substrate, saidmethod comprising: forming a first template layer encompassing apredefined area on a substrate; patterning first openings, each having ashape of a regular hexagon, in said first template layer, wherein saidfirst openings are arranged in a first hexagonal array; applying anon-photosensitive polymeric resist comprising a first polymeric blockcomponent and a second polymeric block component within each of saidfirst openings; forming first nanoscale self-assembled self-alignedstructures in said first openings; forming a second template layerencompassing said area on said first nanoscale self-assembledself-aligned structures; patterning second openings, each having a shapeof said regular hexagon, in said second template layer, wherein saidsecond openings are arranged in a second hexagonal array; applying saidnon-photosensitive polymeric resist within each of said second openings;forming second nanoscale self-assembled self-aligned structures in saidsecond openings; forming a third template layer encompassing said areaon said first and second nanoscale self-assembled self-alignedstructures; patterning third openings, each having a shape of saidregular hexagon, in said third template layer, wherein said thirdopenings are arranged in a third hexagonal array; applying saidnon-photosensitive polymeric resist within each of said third openings;and forming third nanoscale self-assembled self-aligned structures insaid third openings.
 8. A method of forming a nanoscale pattern on asubstrate, said method comprising: forming a first template layerencompassing a predefined area on a substrate; patterning firstopenings, each having a shape of a regular hexagon, in said firsttemplate layer, wherein said first openings are arranged in a firsthexagonal array; forming first nanoscale self-assembled self-alignedstructures in said first openings; forming a second template layerencompassing said area on said first nanoscale self-assembledself-aligned structures; patterning second openings, each having a shapeof said regular hexagon, in said second template layer, wherein saidsecond openings are arranged in a second hexagonal array; forming secondnanoscale self-assembled self-aligned structures in said secondopenings; forming a third template layer encompassing said area on saidfirst and second nanoscale self-assembled self-aligned structures;patterning third openings, each having a shape of said regular hexagon,in said third template layer, wherein said third openings are arrangedin a third hexagonal array; and forming third nanoscale self-assembledself-aligned structures in said third openings, wherein each of saidfirst, second, and third nanoscale self-assembled self-alignedstructures comprises at least one circular cylinder comprising saidfirst polymeric block component and a polymeric matrix comprising saidsecond polymeric block component and laterally abutting said at leastone circular cylinder.
 9. The method of claim 8, wherein each of saidfirst, second, and third nanoscale self-assembled self-alignedstructures further comprises six instances of a third of a circularcylinder, each instance having a volume of one third of a total volumeof said at least one circular cylinder and having an angle of 120degrees at a ridge.
 10. The method of claim 9, wherein said sixinstances and said polymeric matrix laterally abuts a boundary of one ofsaid first, second, and third openings.
 11. The method of claim 8,wherein each of said first, second, and third nanoscale self-assembledself-aligned structures comprises a plurality of circular cylinderscomprising said first polymeric block component and a polymeric matrixcomprising said second polymeric block component and laterally abuttingsaid at least one circular cylinder, wherein each of said plurality ofcircular cylinders is disjoined from boundaries of said first, second,and third openings.
 12. The method of claim 8, further comprisingetching one of a set of said circular cylinders and a set of saidpolymeric matrices selective to the other of said set of said circularcylinders and said set of said polymeric matrices.
 13. The method ofclaim 12, further comprising forming a pattern having sublithographicdimensions in said substrate employing a remaining portion of saidcircular cylinders and said polymeric matrices as an etch mask.
 14. Amethod of forming a nanoscale pattern on a substrate, said methodcomprising: forming a first template layer encompassing a predefinedarea on a substrate; patterning first openings, each having a shape of arectangle and a lithographic width, in said first template layer;applying a non-photosensitive polymeric resist comprising a firstpolymeric block component and a second polymeric block component withineach of said first openings; forming a second template layer directly onsaid first nanoscale self-assembled self-aligned structures; patterningsecond openings, each having a shape of a rectangle and a lithographicwidth, in said first template layer, wherein said second openings are acomplement of said first openings within said predefined area; applyingsaid non-photosensitive polymeric resist within each of said secondopenings; and forming second nanoscale self-assembled self-alignedstructures in said second openings.
 15. The method of claim 14, whereineach of said first and second nanoscale self-assembled self-alignedstructures comprises at least one nominal width line and two edge lines,each comprising said first polymeric component, wherein each of said twoedge lines abut a boundary of one of said first openings, wherein saidat least one nominal width line is disjoined from said two edge lines,wherein said at least one nominal width line has a nominal line widthand said two edge lines have an edge line width, wherein said nominalline width is sublithographic and greater than said edge line width. 16.The method of claim 15, wherein each of said first and second nanoscaleself-assembled self-aligned structures further comprises complementarylines comprising said second polymeric component, wherein each of saidcomplementary lines laterally abuts two of said at least one nominalwidth line and said two edge lines and has another width that issublithographic.
 17. The method of claim 16, further comprising: etchingone of said first polymeric component and said second polymericcomponent selective to the other; and forming a pattern havingsublithographic dimensions in said substrate, wherein said patterncomprises a periodic repetition of at least one first line with a firstsublithographic dimension and a second line with a secondsublithographic dimension, wherein each neighboring pair of said atleast one first line and said second line is separated by a samesublithographic spacing.
 18. A method of forming a nanoscale pattern ona substrate, said method comprising: forming a first template layerencompassing a predefined area on a substrate, wherein an entirety of abottom surface of said first template layer is planar; patterning firstopenings, each having a shape of a rectangle and a lithographic width,in said first template layer; forming first nanoscale self-assembledself-aligned structures in said first openings; forming a secondtemplate layer directly on said first nanoscale self-assembledself-aligned structures; patterning second openings, each having a shapeof a rectangle and a lithographic width, in said first template layer,wherein said second openings are a complement of said first openingswithin said predefined area; and forming second nanoscale self-assembledself-aligned structures in said second openings.
 19. The method of claim18, further comprising: applying a non-photosensitive polymeric resistcomprising a first polymeric block component and a second polymericblock component within each of said first openings prior to said formingof first nanoscale self-assembled self-aligned structures; and applyingsaid non-photosensitive polymeric resist within each of said secondopenings prior to said forming of second nanoscale self-assembledself-aligned structures.
 20. The method of claim 18, wherein each ofsaid first openings and said second openings is patterned by applicationof a photoresist, patterning of said photoresist, and an anisotropicetch that transfers a pattern in said photoresist into one of said firsttemplate layer and said second template layer.
 21. A method of forming ananoscale pattern on a substrate, said method comprising: forming afirst template layer encompassing a predefined area on a substrate;lithographically patterning first openings, each having a shape of arectangle and a lithographic width, in said first template layer;forming first nanoscale self-assembled self-aligned structures in saidfirst openings; forming a second template layer directly on said firstnanoscale self-assembled self-aligned structures; lithographicallypatterning second openings, each having a shape of a rectangle and alithographic width, in said first template layer, wherein said secondopenings are a complement of said first openings within said predefinedarea; and forming second nanoscale self-assembled self-alignedstructures in said second openings.
 22. The method of claim 21, furthercomprising: applying a non-photosensitive polymeric resist comprising afirst polymeric block component and a second polymeric block componentwithin each of said first openings prior to said forming of firstnanoscale self-assembled self-aligned structures; and applying saidnon-photosensitive polymeric resist within each of said second openingsprior to said forming of second nanoscale self-assembled self-alignedstructures.
 23. The method of claim 21, wherein each of said firstopenings and said second openings is lithographically patterned byapplication of a photoresist, patterning of said photoresist, and ananisotropic etch that transfers a pattern in said photoresist into oneof said first template layer and said second template layer.
 24. Themethod of claim 21, wherein an entirety of a bottom surface of saidfirst template layer is planar.